Germanium is distributed widely in the Earth's crust, and is mined primarily for use in the electrical semiconductor
industry. No biological role for germanium has been identified, but methylgermanium
species have been detected in the oceans and are proposed to be of biological origin (reviewed by Thayer,
2002). Research on germanium toxicity and germanium bioaccumulation has been reviewed by
Slawson et al (1992). Bacteria were found to be more tolerant of germanium than yeasts or diatoms, with
diatoms showing the lowest tolerance (possibly due to the incorporation of
germanium in place of silicon into silicate shells). Evidence suggests that germanium accumulation by algae and bacteria
occurs by both active and passive mechanisms.